Surgery for Epilepsy

Of every three patients with epilepsy, one will struggle with seizures that cannot be controlled by medication. If your seizures are difficult to control, you have “drug-resistant” epilepsy. You are likely a candidate for surgery to help control or stop your seizures. Seizures are considered drug-resistant after trying two anti-seizure drugs without success.

Before surgery is an option, several factors must be considered. Generally, surgical candidates include patients who have had:

• poor control of their seizures with two or more medications;
• a clear diagnosis of epilepsy and seizure type;
• patient and family education to ensure they understand the advantages and disadvantages of the surgical procedure or procedures recommended, including medication effects and side effects, as well as alternative treatments.

The purpose of the pre-surgery (also called “preoperative”) evaluation is to determine whether surgery can be performed safely and have a good chance of helping. This requires a detailed presurgical evaluation to identify seizure type, seizure frequency, the site of seizure onset, and psychological and social functioning to select the most appropriate treatment from a variety of surgical options. This type of evaluation is best carried out in a multi-disciplinary epilepsy center experienced in the investigation and treatment of epilepsy, such as Brigham and Women’s Hospital.

If you undergo a presurgical evaluation, a variety of specialists will be involved in your care, including neurologists, neurosurgeons, psychologists, nurses, social workers, EEG technologists, and others.

The surgical evaluation process can take from several weeks to several months, depending on your individual needs. During this process, our entire team considers both the medical and emotional needs of the patient and their family.

The primary components of the pre-surgical evaluation include:

• A detailed clinical history and physical examination.
• A high-resolution MRI scan of the brain.
• Continuous video-EEG monitoring - an inpatient hospital stay for three to seven days for 24-hour video and EEG recordings. The goal is to allow the patient to have their usual seizures in order to localize where the seizures come from. During the admission, the patient's medications may be reduced so that a seizure is more likely to occur.
• Neuropsychological Testing - a neuropsychological assessment can provide essential data that is helpful for identifying areas of altered brain function/thinking that may be related to where the seizures originate. Language function, memory, and visuospatial capability are examined. These tests last several hours and require some patience. By examining the pattern of test results, the neuropsychologist can identify the specific brain areas impacted by the patient’s seizures.
• Assessment of Psychosocial Functioning: Psychological, social and psychiatric assessment plays an important role. With this evaluation, the expectations of surgery and the post-operative adjustment are explored.
• Functional imaging: This is an attempt to see changes in brain metabolism using the uptake of glucose, called "positron emission tomography" (PET scan). A PET scan is used to identify areas of hypometabolism (decreased glucose uptake), which may be associated with a seizure focus. Single photon emission computer tomography (SPECT scan), which looks at blood flow, may also be used.

The various parts of the presurgical evaluation gradually form a clear picture of you and your seizures. Sometimes, the location where seizures start is still unclear after this testing. This can be because the place where seizures start is too deep in the brain to clearly record from the surface. In this case, we may recommend intracranial monitoring.

For intracranial monitoring, we temporarily place electrodes directly on or into the brain. This is typically done with a minimally invasive surgery called stereo-electroencephalography, or “stereo-EEG.” Regular EEG, where electrodes are placed on the scalp, can’t always record brain signals arising deep within the brain, since these signals are muffled by the skin and skull. Stereo-EEG places thin wires—0.8 mm in diameter, about half as thick as a grain of rice—directly within these deep structures. This gives a clear, high-resolution picture of brain activity between and during seizures.

For the stereo-EEG procedure, the patient is placed under general anesthesia. A surgical robot is used to help place each thin wire. When all electrodes are placed, the patient is awoken from anesthesia and admitted to the hospital for several days, like other long-term EEG monitoring sessions. This helps us observe the patient’s natural seizures, capturing them where they start. At the end of the recordings, typically 5 or more days, the electrodes are removed and the patient discharged home.

The Edward B. Bromfield Epilepsy team at Brigham & Women’s Hospital strives to meet the multifaceted medical, psychological, and social needs of individuals and families in order to make the experience of having epilepsy surgery as successful as possible. Our multidisciplinary team includes neurologists, neurosurgeons, neuropsychologists, neuropsychiatrists, epilepsy nurses, neuro-clinical social workers, and EEG laboratory technicians, all defined below.

Neurologist: A physician who specializes in the nervous system, specifically, epilepsy and the brain. After examination and treatment, they may recommend brain surgery for difficult-to-control seizures if there is a strong indication that the electrical discharge is coming from a focal area such as the left or right temporal lobe.

Neurosurgeon: A surgeon specializing in the brain who has expertise in epilepsy surgery. They work closely with the neurologist.

Neuropsychologist: A psychologist specializing in brain and behavior, focusing on the impact of memory, insight and cognition through interview and neuropsychological testing.

Neuropsychiatrist: A psychiatrist specializing in neurological issues and the psychiatric impact of epilepsy.

Clinical Nurse Specialist: A nurse specializing in psychosocial manifestations, pre- and post-surgical care, medication treatment of epilepsy and patient education.

Neuro-Clinical Social Worker: A social worker specializing in the psychosocial issues of epilepsy, pre- and post-surgical care, resources, community programs, and patient education.

EEG Laboratory Technicians: Technicians specializing in brain wave monitoring use for procedures, and required to capture seizures for further diagnosis.

The goal of epilepsy surgery is to find the source of seizures and control them. There are many types of surgery, ranging from removing the tissue causing seizures to devices that modulate seizures without touching the brain directly.

Resection: The most powerful surgery is a resection, where brain tissue causing seizures is removed. This is typically done with a microscope and microsurgical techniques. The most common resection is a “temporal lobectomy.” Success rates of 60-80 percent have been reported, with or without anti-seizure medications.

Laser ablation: A minimally invasive way to remove brain tissue causing seizures is with a laser ablation. Here, a thin laser is temporarily inserted into the brain. This heats up the pathological tissue, burning it. The laser is then removed leaving a small incision closed with 1 or 2 stitches.

Responsive Neurostimulation: In responsive neurostimulation, or RNS, electrodes are placed directly into the brain region causing seizures. These are connected to a miniature implanted computer. This device then listens for seizure-like activity and delivers a burst of electrical stimulation to stop this abnormal activity. Patients have, on average, a 40% reduction in the number of seizures they have in the first year, and better reductions as time passes.

Deep Brain Stimulation: Like RNS, deep brain stimulation (DBS) uses electrodes implanted directly into the brain, connected to a pulse generator in the chest. The pulse generator is similar to a cardiac pacemaker. The reduction in seizures is about 40% in the first few months, with better results as time goes on.

Vagus nerve stimulation: VNS, or vagus nerve stimulation, uses a small coil of wire wrapped around the vagus nerve in the neck. This wire is connected to a small pulse generator in the chest, like a cardiac pacemaker or like DBS. This stimulator affects the vagus nerve, which reduces the chance of seizures. In the first few months, the average number of seizures is reduced by about 30%, with improved performance long-term.